Accompanying organ functional impairment in patients deficient in renal function or hepatic function, poisonous toxins accumulate and are produced in the body such as in the blood, and cause uremia or encephalopathy such as impaired consciousness. Since the number of such patients has shown an increasing trend year by year, the development of therapeutic medicines or organ substitute devices that has the function of removing toxins to outside the body in place of these deficient organs is a critical topic. Removal of poisonous substances by hemodialysis is currently the method most widely used as artificial kidneys. However, such hemodialysis-type artificial kidneys are not necessarily satisfactory due to problems such as the necessity for a specialized technician from the viewpoint of safety management because a special machine is used, and additionally, the high physical, mental and economic burden on the patient due to extracorporeal removal of blood, and the like.
As a means for solving these problems, an oral adsorbent that can be orally ingested and can treat functional impairment of the kidney or liver has been developed and used (Patent Document 1). The oral adsorbent has been widely clinically used in, for example, patients with hepatorenal functional impairment as an oral therapeutic agent that has fewer adverse effects such as constipation. The oral adsorbent contains a porous spherical carbonaceous substance (that is, spherical activated carbon) having a certain functional group, has excellent adsorbance of poisonous substances (that is, -aminoisobutyric acid, □-amino-n-butyric acid, dimethylamine, and octopamine) in the presence of bile acid in the intestines, and also has beneficial selective adsorbance in the sense that it adsorbs little of the beneficial components in the intestines such as digestive enzymes and the like. Furthermore, the adsorbent described in Patent Document 1 uses pitch such as petroleum pitch as a carbon source, and is produced by performing oxidation treatment and reduction treatment after preparation of the spherical activated carbon. The spherical activated carbon that has undergone this oxidation treatment and reduction treatment has been named surface-modified spherical activated carbon.
Additionally, Patent Document 2 discloses that surface-modified spherical activated carbon having an average particle size from 50 μm to 200 μm has excellent initial adsorption ability. That is, in the general residence time (within 3 hours) in the upper small intestine after ingestion of an orally administered adsorbent, it can very rapidly adsorb poisonous toxins (particularly -aminoisobutyric acid) in the body.